Technical Field
The disclosure herein relates to a vane or a blade of a compressor for an aircraft jet engine or a gas turbine engine, and in particular relates to a compressor vane or blade capable of keeping good aerodynamic properties as deposits on surfaces of the vane or the blade naturally exfoliate.
Description of the Related Art
In an aircraft jet engine or a gas turbine engine, its combustor creates high-speed hot gas, its turbine extracts energy from the hot gas, and part of the energy is used to drive its compressor. The compressor sucks ambient air and compresses and supplies it to the combustor. The air is, in the compressor, adiabatically compressed and therefore generates high temperatures about 400-700 degrees C. for example.
While the ambient air contains various types of dust and sand as well as volcanic ash in some cases, it is unavoidable that these substances flow into the compressor. Part of these substances may, along with the compressed air, pass through the compressor and be exhausted out but another part thereof may adhere to the vanes and the blades of the compressor. The ambient air further contains moisture, sulfates, sulfites, chlorides, carbonates and such in the form of gas or minute droplets, which may adhere to the vanes and the blades of the compressor as well. These foreign substances are, by being exposed to high temperatures, physically and chemically changeable into deposits that adhere to the surfaces of the vanes and the blades.
Because an excessive amount of deposits impairs the aerodynamic properties of the compressor vanes and blades, it is necessary to remove them, and, if necessary, re-finish surfaces of the vanes and the blades, in order to restore these original states. Required work includes processes of disassembling the engine, taking out each compressor vane or blade, restoring these original states individually, and re-assembling them into the engine. These laborious processes cause a marked rise in cost about overhauling the engine.
There are some proposals about some arts for coatings to address the problem raised by the deposits. The following literatures disclose related arts. Coatings disclosed therein are intended to prevent adhesion of foreign substances.                United States Patent Application Publication 2010/0247321        United States Patent Application Publication 2010/0086397        